Contingency Events

A Contingency Event is an event affecting the South West interconnected system (SWIS) which AEMO expects would be likely to involve:

a) the failure or removal from operational service of one or more energy producing units, Facilities and/or Network elements; or
b) an unplanned change in load, Intermittent Generation or other elements of the SWIS not controlled by AEMO. A contingency event is an event affecting the power system that AEMO expects would likely involve the failure or removal from operational service of one or more generating units and/or transmission elements.

AEMO is responsible for determining which SWIS events are classified as Credible Contingency Events. This is described in WEM Procedure: Credible Contingency Events.

Credible Contingency Event

A Credible Contingency Event means one or more Contingency Events, the occurrence of which AEMO considers in accordance with the WEM Procedure referred to in clause 3.8A.4 to be reasonably possible in the prevailing circumstances, taking into account the Technical Envelope. Without limitation, examples of Credible Contingency Events include:

a) the unexpected automatic or manual disconnection of, or the unplanned change in output of, one or more operating energy producing units or Facilities;
b) the unexpected disconnection of one or more major items of Network equipment; or
c) Non-credible Contingency Events reclassified as Credible Contingency Events in accordance with the WEM Procedure referred to in clause 3.8A.4.

Non-Credible Contingency Event

A Non-credible Contingency Event means a Contingency Event other than a Credible Contingency Event. Without limitation, examples of Non-credible Contingency Events include simultaneous disruptive events such as:

a) multiple Facility failures; or
b) failure of multiple items of Network equipment

Publication of Events

If any of the information provided to Rule Participants in accordance with clause 3.8A.6 changes in any material respect, AEMO must publish the changes on the WEM Website and notify the affected Rule Participants in accordance with the WEM Procedure referred to in clause 3.8A.4. The data will be available at the WEM Market Data site